Transcript Chapter 7 Body Systems

Dental Unit Waterlines
Chapter 24
Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved.
Chapter 24
Lesson 24.1
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Learning Objectives
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Pronounce, define, and spell the Key Terms.
Discuss why there is a renewed interest in
contamination of dental-unit waterlines
(DUWLs).
Explain why DUWLs contain more bacteria
than faucets do.
Identify the primary source of microorganisms
in dental-unit water.
Explain the role of biofilm in DUWL
contamination.
(Cont’d)
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Learning Objectives
(Cont’d)
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List the factors in bacterial contamination of
dental-unit water.
Describe methods to reduce bacterial
contamination in DUWLs.
Describe the recommendations of the
Centers for Disease Control and Prevention
(CDC) for dental-unit water quality.
Explain the CDC’s recommendation for the
use of saliva ejectors.
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Introduction
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Outbreaks of waterborne disease have
occurred in a broad range of facilities.
Although there is no evidence of a
widespread public-health problem, published
reports have associated illness with exposure
to water from dental units. The fact that
bacteria capable of causing disease in human
beings are found in DUWLs is reason for
concern.
(Cont’d)
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Introduction
(Cont’d)
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In community water, the number of waterborne
bacteria is kept to fewer than 500 colony-forming
units (CFUs) per milliliter.
The water from air-water syringes and dental
handpieces often has bacterial levels hundreds or
thousands of times greater than those permissible in
drinking water.
The types of bacteria that are found in dental-unit
water are frequently the same types found in
community water, but the levels of bacteria found in
the dental units are almost always higher.
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Background
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Dental healthcare workers are exposed to Legionella
bacteria at a much higher rate than are members of
the general public.
Dental personnel are exposed to contaminated
DUWLs through inhalation of the aerosol generated
by the handpiece and air-water syringe.
At least one suspected fatality of a dentist resulting
from legionellosis has been recorded.
Published case reports have described
immunocompromised patients in whom postoperative
infections developed as a result of contaminated
dental water.
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Microorganisms in Waterlines
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The primary source of microorganisms in DUWLs is
the public water supply.
Saliva can be retracted into DUWLs during treatment.
This process is called “suckback.”
Antiretraction valves on dental units and thorough
flushing of the dental lines between patients minimize
the chance of suckback.
The public water source has a CFU count of less
than 500/mL before entering the DUWLs; once that
water enters the DUWLs and colonizes within the
biofilm, the CFU count skyrockets.
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Communities of Bacteria
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There are two communities of bacteria in
DUWLs:
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One bacterial community exists in the water itself
and
is referred to as planktonic (free-floating).
The other exists in the biofilm attached to the walls
of the DUWLs.
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Fig. 24-1 Close-up of a dental tube’s opening.
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Fig. 24-2 A, Magnification of biofilm formation on the walls of the tube.
B, Cross-section of biofilm formation in DUWL.
(Courtesy of Sultan Chemists, Inc, Englewood, NJ.)
A
B
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Fig. 24-3 Bacteria in biofilm taken from DUWLs.
(Courtesy of Dr. Shannon Mills, U.S. Air Force.)
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Biofilm
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Biofilm exists in all places where moisture
and a suitable solid surface are found.
Biofilm consists of bacterial cells and other
microbes that adhere to surfaces and form a
protective slime layer.
Biofilm can contain many types of bacteria, as
well as fungi, algae, and protozoa.
Viruses, such as the human
immunodeficiency virus, cannot multiply in
DUWLs.
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Fig. 24-4 Bacteria in biofilm dropping into waterlines. Some bacteria
are planktonic and enter directly from the municipal water supply.
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Methods of Reducing Contamination
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It is not yet possible to eliminate biofilm, but it
can be minimized with the use of:
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Self-contained water reservoirs
Chemical treatment regimens
Microfiltration
Daily draining and drying of lines
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Self-Contained Water Reservoirs
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These systems supply air pressure to the
water bottle (reservoir).
The air pressure in the bottle forces the water
from the bottle up into the DUWL and out to
the handpiece and air-water syringe.
Self-contained water systems have two
advantages:
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Dental personnel can select the quality of water to
be used (e.g., distilled, tap, sterile).
Maintenance of the water system (between the
reservoir bottle and the handpieces and syringes)
is under the control of the dentist and staff.
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Fig. 24-5 Self-contained dental-water unit.
(Courtesy of Dr. Ronald Johns.)
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Fig. 24-6 Reservoir water bottles and lines on self-contained water systems must be
cleaned and disinfected in accordance with the manufacturer’s instructions. The
container under the water bottle will catch any solution drips. Note: The dental
assistant is careful not to touch and contaminate the neck of the bottle.
(Courtesy of Pamela Landry, RDA.)
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Microfiltration Cartridge
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A disposable inline microfiltration cartridge
can dramatically reduce bacterial
contamination in dental-unit water.
This device must be inserted as close to the
handpiece or air-water syringe as possible.
It should be replaced at least daily on each
line. The use of filtration cartridges combined
with water reservoirs can ensure improved
water quality.
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Fig. 24-7 The DentaPure cartridge releases 2 to 6 ppm of iodine as the water passes
over it. The water delivered to the handpiece water, 3-way water syringe, and ultrasonic
scaler is treated. The cartridges are changed every 40 days.
(Courtesy of DentaPure, Fergus Falls, Minn.)
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Chemical Agents
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Chemicals can be used to help control biofilm
in two ways:
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Periodic or “shock” treatment with biocidal levels (levels that
will kill microorganisms) of chemicals
Continuous application of chemicals to the system (at a level
that will kill the microorganisms but not harm human beings)
Always check with the manufacturer of the dental
equipment to determine which chemical product and
maintenance protocol is recommended.
Monitor the water quality in the dental unit in
accordance with the manufacturer’s
recommendations.
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Water for Surgical Procedures
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Dental-unit water should not be used as an
irrigant for surgery involving the exposure of
bone.
Only use sterile water from special sterile
water–delivery systems or hand irrigation with
sterile water in a sterile disposable syringe.
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Flushing Waterlines
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All DUWLs and handpieces should be flushed
in the mornings and between patients.
Although this will not remove biofilms from the
lines, it may temporarily reduce the microbial
count in the water.
It will help clean the handpiece waterlines of
materials that may have entered from the
patient’s mouth.
Flushing also brings a fresh supply of
chlorinated water from the main waterlines
into the dental unit.
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Minimizing Aerosols
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Always use the high-volume evacuator when
using the high-speed handpiece, ultrasonic
scaler, and air-water syringe.
The high-volume evacuator may also reduce
exposure of the patient to these waterborne
microorganisms.
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Using Protective Barriers
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The dental dam greatly reduces direct
contact.
The dam also greatly reduces the
aerosolization and spattering of the patient’s
oral microorganisms onto the dental team.
Protective barriers, including masks,
eyewear, and face shields, also serve as
barriers for the dental team.
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